The present invention relates to the discovery of methods and compositions for the inhibition of cell growth and migration. More specifically, B19 parvovirus capsids or fragments of B19 parvovirus capsid proteins are used to manufacture medicaments that can be administered to a subject to inhibit the growth and/or migration of cells that have the P antigen, including, but not limited to, cells of hematopoietic origin and endothelial cells.
The B19 parvovirus is a human pathogen that can be associated with various clinical conditions, ranging from mild symptoms (erythema infectiosum) to more serious diseases in persons who are immunocompromised or suffer from hemolytic anemias. Hydrops fetalis and intrauterine fetal death are well-known complications of B19 infection during pregnancy. (Anderson and Young, Monographs in Virology, 20 (1997)). The B19 parvovirus particles have icosohedral symmetry, a diameter of 18 to 26 nm, and are composed of 60 capsid proteins, approximately 95% of which are major capsid proteins (VP2) that have a molecular weight of 58 kd. (Fields et al., Virology vol. 2, 3rd edition, Lipponcott-Raven Publishers, Philidelphia, Pa., p. 2202 (1996)). Approximately, 3-5% of the capsid proteins that compose a B19 parvovirus capsid are called minor capsid proteins (VP1), which have a molecular weight of 83 kd, and differ from VP2 by an additional 227 amino acids at the amino terminus. (Id.).
The B19 parvovirus is extraordinarily tropic for human erythroid cells and cultures of bone marrow. B19 parvovirus binds to human erythroid progenitor cells, for example, and inhibits hematopoietic colony formation by replicating in these cells. (Brown et al., Science, 262:114 (1993) and Mortimer et al., Nature, 302:426 (1983)). The suppression of hematopoietic cells has also been seen in bone marrow samples from infected individuals, resulting in transient anemia and, in rare case, transient pancytopenia. (Saunders et al., Br J Haematol, 63:407 (1986)). Further, B19 parvovirus is known to cause bone marrow suppression in natural and experimental human infections. (Anderson and Young, Monozraphs in Virology, 20 (1997)).
The cellular receptor for B19 parvovirus has been identified as globoside or ertythrocyte P antigen, a textrahexoceramide. Fields et al., Virology vol. 2, 3rd edition, Lipponcott-Raven Publishers, Philidelphia, Pa., p. 2204 (1996)). The P antigen is found on mature erythrocytes, erythroid progenitors, megakaryocytes, endothelium, kidney cortex, placenta, fetal myocardium (von dem Bome et al., Br J Hematol, 63:35 (1986)) and pronormoblasts from fetal liver. (Morey and Flemming, Br J Haematol, 82:302 (1992)). Individuals who genetically lack the P antigen are not susceptible to B19 parvovirus infection and administration of either excess P antigen or monoclonal antibodies directed to the P antigen can protect erythroid progenitors from infection with B19 parvovirus. (Id.).
Additionally, neutralizing antibodies that recognize several regions of the B19 parvovirus particle have been generated. For example, monoclonal antibodies directed to epitopes of VP2, such as found at amino acids 38-87, 253-272, 309-330, 328-344, 359-382, 449-468, and 491-515, and the unique region of VP1 can neutralize B19 parvovirus. (Fields et al., Virology vol. 2, 3rd edition, Lipponcott-Raven Publishers, Philidelphia, Pa., p. 2207 (1996)).
Genetically engineered expression systems for the production of B19 parvovirus antigens have also been developed. (Kajigaya et al., Proc Natl Acad Sci USA, 86:7601 (1989); Kajigaya et al., Proc Natl Acad Sci USA, 88:4646 (1991); Brown et al., J Virol, 65:2702 (1991)). Like the native particles, recombinant B19 parvovirus capsids, produced in a baculovirus system, are composed of both VP1 and VP2 and these capsid proteins self assemble to form virus-like particles (VLPs). (Kajigaya et al., Proc Natl Acad Sci USA, 88:4646 (1991)). Electron microscopic analyses of the B19 parvovirus capsids revealed that the VLPs are structurally similar to plasma-derived virions. (Kajigaya et al., Proc Natl Acad Sci USA, 88:4646 (1991)). B19 VLPs are currently being evaluated as a potential vaccine against B19 parvovirus infection and preliminary results show a good neutralizing response without severe side effects. (Bostic et al, J Infect. Dis., 179:619 (1999). While many are trying to prevent B19 parvovirus infection by administering B19 capsids, none have sought to exploit the properties of the B19 parvovirus capsid, B19 capsid proteins, or fragments thereof to develop novel medicaments that inhibit cell proliferation or migration.
In the invention described herein, the inventors disclose the discovery that the B19 parvovirus capsid, B19 parvovirus capsid proteins, or fragments thereof inhibit the growth and/or migration of cells that have the P antigen. Embodiments of the invention include medicaments comprising B19 parvovirus capsid, B19 parvovirus capsid proteins, or fragments thereof that can be administered to subjects in need of an agent that inhibits cell growth and/or migration. Methods of treatment of diseases or conditions associated with hematopoietic or endothelial cell proliferation or migration are also within the scope of aspects of the invention.
One embodiment, for example, involves the use of empty, noninfectious, recombinant B19 parvovirus capsids, B19 capsid proteins, or fragments of B19 capsid proteins for the production of a medicament for the inhibition of growth or migration of cells that have the P antigen. The medicament, according to this use, can be for the inhibition of hematopoietic cell growth, endothelial cell growth, or endothelial cell migration. Additionally, the medicament according to this use can be for the treatment of hematological proliferative disorders, angiogenesis, tumorigenesis, or endothelial cell ingrowth into an implanted prosthetic device. Further, the medicament according to this use can be for treatment of a subject prior to stem cell transplantation and the subject can be a fetus.
In another embodiment, a method of inhibiting the growth or migration of a cell having the P antigen is provided. This method comprises the steps of contacting a cell with a capsid agent selected from the group consisting of B19 parvovirus capsid, B19 capsid protein, and a fragment of a B19 capsid protein and measuring the inhibition of cell growth or cell migration. In some aspects, the cell can be a cell of hematopoietic origin or an endothelial cell.
A method of treating a subject prior to stem cell transplantation is also embodied in the invention. This method is performed by identifying a subject in need of a capsid agent that inhibits hematopoietic cell growth and providing said subject in need with an effective amount of capsid agent selected from the group consisting of B19 parvovirus capsid, B19 capsid protein, and a fragment of a B19 capsid protein. Similarly, a related embodiment, concerns a method of treating a subject for a hematopoietic proliferative disorder comprising the steps of identifying a subject in need of a capsid agent that inhibits a hematopoietic proliferative disorder and providing said subject in need with an effective amount of capsid agent selected from the group consisting of B19 parvovirus capsid, B19 capsid protein, and a fragment of a B19 capsid protein.
A method of inhibiting tissue ingrowth into an implanted prosthesis is also provided. This approach comprises the steps of identifying a subject in need of a capsid agent that inhibits tissue ingrowth into an implanted prosthesis and providing said subject in need with an effective amount of capsid agent selected from the group consisting of B19 parvovirus capsid, B19 capsid protein, and a fragment of a B19 capsid protein. Another embodiment involves a method of treating or preventing tumorigenesis and this method comprises the steps of identifying a subject in need of a capsid agent that inhibits hematopoietic cell growth and providing said subject in need with an effective amount of capsid agent selected from the group consisting of B19 parvovirus capsid, B19 capsid protein, and a fragment of a B19 capsid protein.
A kit having a capsid agent is also an embodiment and one such kits comprises a capsid agent selected from the group consisting of B19 parvovirus capsid, B19 capsid protein, and a fragment of a B19 capsid protein and instructions for dosage and administration to a subject for hematopoietic progenitor cell growth inhibition, hematopoietic progenitor cell growth inhibition, endothelial cell growth inhibition or treatment of a hematological proliferative.